Opposition Senator Leila M. de Lima has pushed for a Senate investigation into the practice of some unscrupulous police officers to plant evidence at the crime scenes during their buy-bust operations to easily prosecute suspected drug offenders.

De Lima, a known human rights defender, filed Senate Resolution (SR) No. 600 urging the appropriate Senate committee to look into several reports alleging that some members of the Philippine National Police (PNP) have been staging the crime scenes.

"It is incumbent upon the PNP to make sure procedures in collection and preservation of evidence are lawfully adhered to in all stages of police investigation, and duly sanction those who err to fulfill this mandate," she said.

"It is a grave injustice to accuse anyone of a crime - worse, kill him - without giving him the chance to defend himself before the court," she added.

The former justice secretary cited several reports where the arresting officers purportedly planted evidence at the crime scenes to justify their killings of suspected offenders.

Last Sept. 8, she recalled that Public Attorney's Office (PAO) forensic lab chief Erwin Erfe reportedly claimed that the crime scene where 19-year-old Carl Arnaiz was killed was apparently staged.

This was after PAO re-examined the crime scene on Sept. 7 in which they concluded that "there were no traces of blood... it was a secondary crime scene."

De Lima also cited Reuters' report last April when two undisclosed senior PNP officials revealed that the PNP has received cash payments for executing drug suspects, planting evidence at crime scenes and carrying out most of the killings they have long blamed on vigilantes.

"The Senate investigation is important to shed light on these disturbing trends," she said.

The Senator from Bicol asked her Senate colleagues to look into the measures being taken by the PNP to preserve evidence and to ensure their proper handling and safekeeping at all stages of the investigation.

"In order to start regaining people's trust and to maintain the integrity and stringency of police investigation, the PNP should never, in any circumstances, tamper with evidence and undermine eyewitness testimonies," she noted.

In another bill she filed, Senate Bill 1364, De Lima also sought the preservation and protection of data recorded by security cameras that would serve not only as possible leads in identifying and apprehending criminals but also as evidence to build cases against them.